1. Field of the Invention
The present invention relates generally to a pressure control valve, which is useful in an automotive power steering system or other industrial facilities.
2. Description of the Background Art
A pressure control valve of this type has been disclosed in Japanese Patent First (unexamined) Publication (Tokkai) Showa 63-231003, for example. Such a conventional pressure control valve has a valve bore in a valve body. A valve spool is disposed for thrusting movement within the valve bore for adjusting fluid flow rate through a supply line, output line and drain line. The valve spool is associated with an electromagnetic solenoid to be driven in a direction for increasing the output pressure in the output line. The valve spool is also associated with a feedback means for providing feedback pressure for returning to the initial position. Furthermore, the valve spool is normally biased toward an initial position by means of a set spring.
In such a conventional pressure control valve, the force for driving the valve spool is generated in the solenoid and transmitted to the valve spool via an actuation rod. Such construction clearly limits reduction of the axial length of the valve assembly. In addition, in the prior proposed construction, the set spring is disposed between the valve spool and a casing of the solenoid. Therefore, in order to adjust the set pressure, an axial position of the solenoid casing has to be adjusted. This makes adjustment of the set load difficult and complicated.